Assessment of shoulder strength in professional baseball pitchers

Study Design: A bilateral comparison of strength and range of motion testin g in professional baseball pitchers. Objective: We studied 39 professional male baseball pitchers to determine i f the shoulder used for throwing was weaker or had less passive range of mo tion, compared to the nondominant arm. Background: Shoulder muscle weakness has been proposed as a possible risk f actor for developing injury. Therefore, objective quantification of the str ength of glenohumeral and scapular rotator muscle groups should be studied in a population of professional baseball pitchers. Methods and Measures: Passive internal and external range of motion was bil aterally measured at 90 degrees of abduction. Muscle strength of the follow ing muscles was measured bilaterally with a hand-held dynamometer: external and internal glenohumeral rotators, supraspinatus, middle trapezius, lower trapezius, and serratus anterior. Results: Passive external rotation of the glenohumeral joint at 90 degrees of abduction on the pitching side was significantly greater than on the non pitching side. Passive internal rotation range of motion on the nonpitching side was significantly greater than on the pitching side. The pitching arm 's internal rotators, when tested in abduction, were significantly stronger than the nonpitching arm. The nonpitching arm's external rotators in the p lane of the scapula, and in abduction, were significantly greater than thos e of the pitching arm. The pitching arm's middle and lower trapezius muscle s were significantly stronger than those of the nonpitching arm. Conclusion: The range of motion and strength characteristics measured in th is study can assist clinicians in evaluating athletes who use overhead thro wing motions.